IOSR Journal of Electrical and Electronics Engineering (IOSR-JEEE) e-ISSN: 2278-1676,p-ISSN: 2320-3331, Volume 10, Issue 2 Ver. I (Mar – Apr. 2015), PP 34-42 www.iosrjournals.org DOI: 10.9790/1676-10213442 www.iosrjournals.org 34 | Page Simulation of Four Quadrant Operation of Sensor less BLDC Motor 1 Praveen Kumar C, 2 Sobi Soman 1 Asst .Professor EEE Dept . NSS College Of Engineering , Palakkad 2 PG Scholar NSS College Engineering , Palakkad Abstract: This paper gives a control for three phase Sensor less brushless DC (BLDC) motor in all four quadrant operation. The control system in this paper is capable to detect and identify the rotor position by sensor less method signal. In this paper behaviour of BLDC motor is studied in all four quadrant operations through simulation model. The simulation is carried out for four quadrant operation and during regenerative braking kinetic energy is wasted as heat energy. This paper gives utilization of wasted kinetic energy is converted and stored in battery. The simulation model shows the control for four quadrant operation without sensor. From this paper during regenerative braking instead of wasting kinetic energy can be considerable as saving of power. Keywords: BLDC motor; Four quadrant operation; regenerative braking; Digital controller Introduction I. Introduction Brushless DC motor has a rotor with permanent magnets and a stator with windings. It is essentially a DC motor turned inside out. The brushes and commutator have been eliminated and the windings are connected to the control electronics. An electronic controller replaces the brush/commutation assembly of the brushed DC motor, which continually switches the phase to the windings to keep the motor turning. The controller performs similar timed power distribution by using a solid-state circuit rather than the brush/commutation system .The motor has less inertia, therefore easier to start and stop. BLDC motors are potentially cleaner, faster, more efficient, less noisy and more reliable. The Brushless DC motor is driven by rectangular or trapezoidal voltage strokes coupled with the given rotor position. The voltage strokes must be properly aligned between the phases, so that the angle between the stator flux and the rotor flux is kept close to 90 to get the maximum developed torque. BLDC motors is also known as synchronous devices because the magnetic fields of the stator and rotor rotate at the same frequency. The stator comprises steel laminations, slotted axially to accommodate an even number of windings along the inner periphery. The rotor is constructed from permanent magnets with from two- to-eight N-S pole pairs. BLDC motors are used in Automotive, Aerospace, Consumer, Medical, Industrial automation equipments and instrumentation. Fig 1 Shows the cross sectional View of BLDC motor The BLDC motor‘s electronic commutator sequentially energizes the stator coils generating a rotating electric field that ‗drags‘ the rotor around with it. Efficient operation is achieved by ensuring that the coils are energized at precisely the right time. This paper also deals with the speed control of BLDC motor. Generally the rotor position can be sensed by the hall effect sensor or any other explicit method like zero crossing detection method ,inductance method etc also. Hall sensors work on the hall-effect principle that when a current-carrying conductor is exposed to the magnetic field, charge carriers experience a force based on the voltage developed across the two sides of the conductor. If the direction of the magnetic field is reversed, the voltage developed